Active Filter Design:Active Filter Design:

By: Benjamin GrydehoejBy: Benjamin GrydehoejNapierNapier University University

Active Filter Design:Active Filter Design:

Requirement for the Butterworth filter:Requirement for the Butterworth filter:

Data:Data:• -3 dB Pass band Attenuator• 3.4 KHz Pass band frequency• 6.0 KHz Stop band frequency• 10 dB Stop band Attenuator• 6 dB Pass band Gain

Active Filter Design:Active Filter Design:

Types of Types of filtersfilters::

Active Filter Design:Active Filter Design:

Sallen-key:Sallen-key:

This circuit has a phase orientation of 0 degreeThe Gain is chosen by R3 & R4

Active Filter Design:Active Filter Design:

Multiple Feedback: (MFB)Multiple Feedback: (MFB)

This circuit has a phase orientation of 180 degreeThe Gain is chosen by R1 & R2

Active Filter Design:Active Filter Design:Measurement:Measurement:

Active Filter Design:Active Filter Design:Gain frequency Resopnse graph for Sallen-key:Gain frequency Resopnse graph for Sallen-key:

Ideal

Non Ideal

Practical

-3dB Practical

-10dB Practical

1000 10000

-40

-30

-20

-10

0

f

dB

Active Filter Design:Active Filter Design:Gain frequency Resopnse graph for MFB:Gain frequency Resopnse graph for MFB:

Ideal

Non Ideal

Practical

-3dB Practical

-10dB Practical

1000 10000

-40

-30

-20

-10

0

f

dB